Tread Wear Guide: How to Check Tire Tread Depth

By Tire Agent Staff

October 10, 2024

This post answers common concerns about replacing tires, including:

How much tread is on a new tire
How to measure tire tread
What is the minimum tread depth for tires
How to check tires with a penny
How to read tire wear indicator
How to measure tire depth with a gauge

There are three conditions that determine when it’s time to replace tires:

Age: Replace tires after six years, even if they’re within the mileage warranty and even if they have tread depth that is within the acceptable range. Read more about tire age.
Damage: Sidewall punctures and cracks cannot be safely repaired; replace tires that have sidewall damage. Read more about tire shoulders and sidewalls.
Tread depth: This post explains tread depth, how much tires should have, and how to know when your tread depth is telling you it’s time to buy new tires.

3 Tire Tread Tests You Can DIY

Check tire tread depth every 3,000 miles (or if it’s easier to remember, do it with every oil change). Here are three ways to quickly get the job done.

1. Tire penny test: How to use a coin to check tire tread

So, what’s the easiest way to check tread depth without a gauge? Most people would agree it’s the penny test. Checking tire tread with a penny is very simple.

Insert a penny into your tire’s tread groove with Lincoln’s head upside down. Make sure Lincoln is facing you. If you can see all of Lincoln’s head, your tire tread depth is less than 2/32 inch, and it’s time to replace your tires.

You can also do the test with a quarter. Insert a quarter into your tire’s tread groove with Washington’s head facing down and toward you. If the tread surpasses the top of Washington’s head, it’s above 4/32 of an inch and is in good shape.

Don’t check just one point on a tire — check several points to ensure even wear of your tire.

If the tread is flush with the top of Washington’s head, it’s at 4/32 of an inch. Now you’re on the borderline of safety, and it’s time to start thinking about replacing the tire. The low tread isn’t safe because it leads to reduced traction, increasing the distance needed to stop and putting you at a greater risk of getting a flat.

2. Built-in tread wear indicators

Most modern tires have built-in visual marks to help you know when to replace them. These are called tire wear bars, indicators and markers, which are built into the tire itself.

Continental’s tires have a D-W-S embossed, which means when the S is worn the tire is no longer safe in snow; when the W is worn, it’s no longer safe for wet driving; and when the D is worn, it’s no longer safe in dry conditions either.

Built-in tire indicators are spaced evenly throughout the tire’s tread so that as the tire wears closer to that 2/32 inch mark, the wear bar becomes more visible. When the tread is even with the wear bar, it’s time to replace the tire.

Want more details on tread wear indicators? Check out our article on how to read tread wear indicator bars.

3. Tire tread depth gauge

While the coin test and tread bar indicators are very reliable ways to check your tires’ depth, the most reliable way to check is with a gadget called a tire tread depth gauge. A tire gauge isn’t necessary, unless you’re into gadgets and math, and, hey, no judgment here.

You can find tire tread depth gauges for purchase online or at your local auto parts store. They are super easy to use.

Simply measure your tire’s tread depth by sticking the probe into the shallowest groove on the tire. Then, press the probe’s shoulders flat against the tread and read the results. Easy peasy.

Tire Wear Indicator Chart

This is the generally accepted vehicle tire tread depth chart. A tire with a tread depth of 8/32” or higher is considered in good condition. As your tread depth approaches 4/32”, it is time to start shopping for replacement tires. “Legal” tread depth is considered 4/32” or higher.

Here’s how to interpret the measurements:

6/32 of an inch or higher: Your tire’s tread depth is adequate.
5/32 of an inch: Consider replacing your tires, especially if you drive on snow-covered roads.
4/32 of an inch: If you drive on wet roads, replace your tires.
3/32 of an inch: Your tires are almost worn out, and it’s seriously time to replace them.
2/32 of an inch or lower: You’re now in the danger zone with legally bald tires. Replace them ASAP.

Below is tread size in mm (millimeters):

2/32” = 1.59 mm
3/32” = 2.38 mm
4/32” = 3.18 mm
5/32” = 3.97 mm
6/32” = 4.76 mm
7/32” = 5.56 mm
8/32” = 6.35 mm
9/32” = 7.14 mm
10/32” = 7.94 mm
11/32” = 8.73 mm
12/32” = 9.53 mm
13/32” = 10.32 mm
14/32” = 11.11 mm
15/32” = 11.91 mm

How Much Tread Does a New Tire Have?

New tires typically come with a tread depth ranging from 10/32 to 12/32 inches (or about 8 to 10 millimeters), depending on the tire type and its intended use. This depth is essential for optimal grip, handling, and safety on the road.

Here’s a breakdown of how much tread should be on a new tire by type:

All-terrain tires that are designed for on- and off-roading typically have the deepest treads because they need the best traction on dirt, gravel, mud and snow. They’re typically 12/32 to 15/23 inches.
Passenger all-season car tires are typically between 10/32 to 11/32 inches.
Summer tires are typically around 8/32 to 10/32 inches and have shallower tread depth because they are optimized for grip, precision and responsiveness on smooth surfaces.
Truck and SUV tires tend to have deeper treads, around 11/32 to 12/32 inches, especially if they are all-terrain or off-road tires.
Winter tires, designed for snow and ice, often come with even deeper treads, sometimes up to 12/32 inches, to improve traction in harsh conditions.

It’s worth noting that as tires wear down, they lose grip and performance. Once tread depth reaches 2/32 inches, it’s considered legally bald in many areas, and replacement is highly recommended for safety reasons. For most drivers, replacing tires when tread depth falls below 4/32 inches ensures better performance, particularly in wet or snowy conditions.

Regular tread depth checks and tire rotation can extend the lifespan and maintain the performance of your tires.

How Does Tire Tread Depth Affect Acceleration Times?

Not only does tire tread depth affect your safety, but it also affects the acceleration, handling and even gas mileage.

Tire tread depth has a significant impact on acceleration times. Slick tires, designed specifically for dry racing conditions, offer better traction in certain environments. However, if you were to attempt to accelerate briskly with a standard bald road tire, you would likely struggle to maintain traction. Insufficient tread depth can prevent even the most powerful and fastest cars from effectively channeling their power to the road.

Treads on a tire play a crucial role, akin to claws, in providing constant traction with the surface. As the tread depth decreases over time, these essential “claws” start to wear out and become inconsistent. Consequently, your ability to maintain consistent traction, especially during a standing start, becomes compromised. Inconsistent tread depth directly translates to inconsistent traction, ultimately affecting acceleration times.

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